Men had greater clinical response rates and were more likely to achieve remission with ixekizumab compared with women, according to study findings published in Rheumatology and Therapy.
Data from 2 randomized, placebo-controlled phase 3 trials that evaluated the efficacy of ixekizumab for adult patients with PsA were used. Participants in both trials were randomized to receive either ixekizumab 80 mg every 4 weeks, ixekizumab 80 mg every 2 weeks, or placebo. Clinical response rates were assessed at regular intervals.
After week 24, all participants were randomized again to receive ixekizumab every 4 weeks or every 2 weeks through week 156. Efficacy was measured as the proportion of patients achieving 20%, 50%, or 70% improvement from baseline per the American College of Rheumatology criteria (ACR20/50/70). Achievement of minimal or very low disease activity (MDA/VLDA) or Disease Activity Index for Psoriatic Arthritis (DAPSA) scores of 14 or lower (LDA) or 4 or lower (remission) were also considered for efficacy endpoints. Changes from baseline in disease activity were assessed for all patients. Further analyses were performed for subgroups defined by participant sex.
The pooled cohort comprised 679 patients (mean age 51.0 years; 45.7% men, 54.3% women). Patients were randomized to receive placebo (n=224), ixekizumab every 4 weeks (n=229), or ixekizumab every 2 weeks (n=226). In the pooled cohort, women were older and had greater baseline disease activity per tender joint counts, the Health Assessment Questionnaire Disability Index, and the Leeds Enthesitis Index. Ixekizumab outperformed placebo in both active treatment arms. However, women had smaller numeric improvements from baseline compared with men. In the group receiving ixekizumab every 2 weeks, the proportion of women achieving ACR70 at week 156 was 28.1% compared with 41.2% among men (P <.05). Similarly, women in this group were less likely to achieve MDA (29.7% vs 49.4%; P <.01), VLDA (9.9% vs 21.6%; P <.05), and a DAPSA score of 4 or less (17.3% vs 31.4%) at week 156 compared with men.
Trends were comparable in the group receiving ixekizumab every 4 weeks, with women significantly less likely to achieve ACR50 (38.3% vs 53.8%; P <.05), MDA (26.8% vs 44.9%; P <.01), VLDA (10.2% vs 21.5%; P <.05), a DAPSA score of 14 or less (48.4% vs 62.7%; P <.05), and a DAPSA score of 4 or less (16.8% vs 28.4%; P <.05) at week 156.
Study limitations included the fact that the analyses were not sufficiently powered to adjust for baseline differences between men and women, including differing disease activity levels.
The study authors concluded, “Continued efforts to understand sex differences in treatment response may provide insights that can help optimize clinical decision making.”
Disclosure: Several study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
Eder L, Tony HP, Odhav S, et al. Responses to ixekizumab in male and female patients with psoriatic arthritis: results from two randomized, phase 3 clinical trials. Rheumatol Ther. Published online April 9, 2022. doi:10.1007/s40744-022-00445-w